Standardize os result dataclass documentation

[cmaloney]

Documentation

• Document times_result and waitid_result with members explicitly. Note the returned module name varies depending on environment (Ex. nt.times_result vs. posix.times_result)
• Between class definition and flag sentences add a sentence referring back to the function that uses the flags (ex. os.wait* + os.WCONTINUED, os.preadv + os.RWF_HIPRI)
• For each dataclass like type ensure there are references to the functions which can produce it.

Spotted by @serhiy-storchaka in #151301 (review)

[serhiy-storchaka]

Note the returned module name varies depending on environment

I noticed this in the pydoc output. This is a separate issue. All these classes should have module os.